Book Image

C# 7 and .NET: Designing Modern Cross-platform Applications

By : Mark J. Price, Ovais Mehboob Ahmed Khan
Book Image

C# 7 and .NET: Designing Modern Cross-platform Applications

By: Mark J. Price, Ovais Mehboob Ahmed Khan

Overview of this book

C# is a widely used programming language, thanks to its easy learning curve, versatility, and support for modern paradigms. The language is used to create desktop apps, background services, web apps, and mobile apps. .NET Core is open source and compatible with Mac OS and Linux. There is no limit to what you can achieve with C# and .NET Core. This Learning Path begins with the basics of C# and object-oriented programming (OOP) and explores features of C#, such as tuples, pattern matching, and out variables. You will understand.NET Standard 2.0 class libraries and ASP.NET Core 2.0, and create professional websites, services, and applications. You will become familiar with mobile app development using Xamarin.Forms and learn to develop high-performing applications by writing optimized code with various profiling techniques. By the end of C# 7 and .NET: Designing Modern Cross-platform Applications, you will have all the knowledge required to build modern, cross-platform apps using C# and .NET. This Learning Path includes content from the following Packt products: • C# 7.1 and .NET Core 2.0 - Modern Cross-Platform Development - Third Edition by Mark J. Price • C# 7 and .NET Core 2.0 High Performance by Ovais Mehboob Ahmed Khan
Table of Contents (25 chapters)
Title Page
Copyright
About Packt
Contributors
Preface
16
Designing Guidelines for .NET Core Application Performance
Index

Defining local functions


A language feature introduced in C# 7 is the ability to define a local function. Local functions are the method equivalent to local variables. In other words, they are methods that are only visible and callable from within the containing method in which they have been defined. In other languages, they are sometimes called nested or inner functions.

We will use a local function to implement a factorial calculation.

Add the following code to the Person class:

// method with a local function 
public static int Factorial(int number) 
{ 
   if (number < 0) 
   { 
      throw new ArgumentException( 
        $"{nameof(number)} cannot be less than zero."); 
   }
   return localFactorial(number);

   int localFactorial(int localNumber) 
   {
      if (localNumber < 1) return 1;
      return localNumber * localFactorial(localNumber - 1);
   }
}

Note

Local functions can be defined anywhere inside a method: the top, the bottom, or even somewhere in the middle!

In the Program...